Just curious how long an adult person can stay in an average small (W=2.5metre x L=3.5m x H=2.4m) bedroom with the door & window shut before CO2 levels become dangerous? And what about a small room like ~ w1.4m x L1.4m x h1.6m? I assume the small size would make a dramatic difference? Because co2 is heavier would most of it sink to the floor? any input is appreciated thanks.